Table 4.

Percent Change in Heart Rate Variability per 10-μg/m³ Increase in lag_0-1 PM₁₀ Concentration, at High and Low Measures of Glucose Homeostasis, the Environmental Epidemiology of Arrhythmogenesis in the Women's Health Initiative, 1993–2004^a

Measure of Heart Rate Variability and Glucose Homeostasis	Diabetesb (n = 770c)			Impaired Fasting Glucoseb (n = 1,559c)			Normal Fasting Glucoseb (n = 3,141c)
	Percent Changed	95% Confidence Interval	Pinteractione	Percent Changed	95% Confidence Interval	Pinteractione	Percent Changed	95% Confidence Interval	Pinteractione
RMSSD
Insulin
High	−16.9	−23.4, −9.9	<0.01	−8.3	−13.9, −2.4	<0.01	−0.1	−4.1, 4.0	1.00
Low	−1.9	−5.1, 1.5		−0.6	−2.4, 1.3		−2.3	−4.0, −0.6
HOMA-IR
High	−24.5	−33.3, −14.6	<0.001	−8.4	−13.8, −2.7	<0.01	−1.3	−5.3, 2.9	1.00
Low	0.3	−2.9, 3.7		−0.3	−2.1, 1.6		−2.2	−3.9, −0.4
Glucose
High	−15.7	−25.7, −4.4	<0.01	−4.3	−9.4, 1.0	0.16	−0.8	−4.3, 2.9	0.33
Low	−1.8	−5.0, 1.4		−0.8	−2.7, 1.0		−2.3	−4.0, −0.5
SDNN
Insulin
High	−16.8	−23.5, −9.5	<0.01	−7.4	−12.9, −1.6	0.02	1.8	−2.1, 5.9	0.36
Low	−0.6	−3.5, 2.5		−0.1	−1.6, 1.4		−1.3	−2.9, 0.4
HOMA-IR
High	−21.5	−29.4, −12.7	<0.001	−5.4	−11.0, 0.5	0.08	1.8	−2.0, 5.7	0.37
Low	0.8	−2.1, 3.9		−0.1	−1.6, 1.3		−1.3	−2.9, 0.4
Glucose
High	−11.8	−20.8, −1.7	0.04	−0.4	−5.1, 4.5	0.89	−0.3	−4.1, 3.7	0.66
Low	−1.1	−4.0, 1.8		−0.9	−2.4, 0.7		−1.2	−2.7, 0.5
RR
Insulin
High	−2.4	−4.2, −0.5	<0.01	−0.7	−1.9, 0.4	0.16	−0.4	−1.1, 0.3	0.88
Low	−0.8	−1.5, −0.1		0.3	−0.1, 0.7		−0.4	−0.8, −0.1
HOMA-IR
High	−3.2	−5.7, −0.6	<0.001	−1.1	−2.2, 0.0	0.02	−0.5	−1.2, 0.2	0.92
Low	−0.7	−1.4, 0.0		0.4	0.0, 0.8		−0.4	−0.8, −0.1
Glucose
High	−3.0	−5.4, −0.6	<0.001	−0.3	−1.2, 0.6	0.42	−1.6	−2.2, −0.9	<0.01
Low	−0.7	−1.4, 0.0		0.2	−0.2, 0.6		−0.3	−0.6, 0.0

Abbreviations: HOMA-IR, insulin resistance according to homeostatic model assessment; PM₁₀, particulate matter of <10 μm in diameter; RMSSD, root mean square of successive differences in normal-to-normal RR intervals; RR, median RR interval across all 12 leads; SDNN, standard deviation of normal-to-normal RR intervals.

^aHigh values of insulin, HOMA-IR, and glucose defined as >90th percentile.

^b“Diabetes” is defined as antidiabetic medication use, a fasting glucose level of ≥126 mg/dL (7.0 mmol/L), or history; “impaired fasting glucose” is a glucose level of 100–125 mg/dL (5.6–6.9 mmol/L); and “normal fasting glucose” is a fasting glucose level of ≤99 mg/dL (5.5 mmol/L).

^cUnweighted number of participants with diabetes, impaired fasting glucose, or normal fasting glucose at visit 1, 2, or 3.

^dWeighted for sampling design and adjusted for age (year), race/ethnicity, education, time of day (minutes), day of week, season, body mass index (kg/m²), hypertension, systolic blood pressure (mm Hg), β-blocker use, total energy expenditure (kcal/kg × weeks), current smoker status, chronic lung disease, hypercholesterolemia, coronary heart disease, revascularization, congestive heart failure, lag_0-1 temperature (°C), dew point (°C), and barometric pressure (kPa). Indicators were used to represent the categorical variables in Table 1.

^eP value for the test of the PM₁₀ × insulin, PM₁₀ × HOMA-IR, or PM₁₀ × glucose interaction.